{"gene":"KATNAL1","run_date":"2026-04-28T18:06:54","timeline":{"discoveries":[{"year":2012,"finding":"KATNAL1 (Katanin p60 subunit A-like 1) functions as a microtubule-severing protein in testicular Sertoli cells; a point mutation in its conserved ATPase domain causes loss of function, disrupting Sertoli cell microtubule dynamics and leading to premature spermatid exfoliation from the seminiferous epithelium and male-specific infertility.","method":"ENU mutagenesis screen in mice, identification of ATPase domain point mutation, loss-of-function phenotypic analysis, Sertoli cell expression confirmed from 15.5 dpc","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 — clean loss-of-function allele with defined molecular lesion (ATPase domain) and specific cellular phenotype, replicated with chemical disruption models","pmids":["22654668"],"is_preprint":false},{"year":2017,"finding":"Loss-of-function of KATNAL1 in mice causes defects in motile cilia of ventricular ependymal cells, neuronal migration defects, and morphological brain abnormalities, establishing a role for KATNAL1 in ciliary function and CNS development.","method":"Mouse loss-of-function allele characterization, brain morphology analysis, ependymal cilia imaging, neuronal migration assays","journal":"Molecular psychiatry","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO mouse with defined cellular phenotypes (cilia, neuronal migration), single lab","pmids":["28373692"],"is_preprint":false},{"year":2018,"finding":"KATNAL1 exhibits higher microtubule-severing activity and greater intracellular stability compared to its paralog KATNA1, is dominantly expressed in neurons, and its amino-terminal half region is the determinant of these functional characteristics; KATNAL1 knockdown in Neuro2a cells enhances process elongation whereas KATNA1 knockdown has no effect.","method":"Comparative expression analysis across tissues, microtubule-severing activity assays in Neuro2a cells, cycloheximide chase for stability, chimeric molecule domain-swap experiments, siRNA knockdown with process elongation readout","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro activity assay, domain-swap mutagenesis, stability assay, and KD phenotype all in one study","pmids":["30448058"],"is_preprint":false},{"year":2023,"finding":"KATNAL1 cooperates with KATNA1 to regulate the male meiotic spindle, cytokinesis, midbody abscission, and spermatid remodelling events (Golgi organisation, acrosome and manchette formation); KATNAL1 has specific roles in sperm flagellum development, manchette regulation, and sperm-epithelial disengagement. Proteomic approaches defined the KATNAL1/KATNA1/KATNB1 mammalian testis interactome, which includes cytoskeletal and vesicle trafficking proteins.","method":"Single and double gene knockout mice, proteomic interactome analysis (mass spectrometry), phenotypic characterization of meiosis and spermiogenesis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — multiple single/double KO models plus MS-based interactome, orthogonal methods in one study","pmids":["37882691"],"is_preprint":false},{"year":2024,"finding":"miR-548az-5p targets KATNAL1 mRNA in human amniotic epithelial cells; suppression of KATNAL1 by miR-548az-5p disorganizes microtubules, increases senescence-associated secretory phenotype markers, and inhibits cell proliferation via cyclin D1 and CDK6, contributing to amniotic membrane senescence during labor.","method":"miRNA microarray, bioinformatics target prediction, miR-548az-5p overexpression with KATNAL1 measurement, microtubule imaging, senescence marker assays, proliferation assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, functional miRNA-target validation with downstream cellular readouts but no reciprocal rescue experiment for full mechanistic confirmation","pmids":["39638877"],"is_preprint":false},{"year":2014,"finding":"The MIT domain of KATNAL1 is predicted to be essential for protein function; a splice variant (KATNAL1-TV2) lacking the MIT domain is non-functional, and a promoter SNP (c.163-210T>C) in the alternative promoter P2 increases expression of this non-functional isoform, correlating with higher sperm deformity rates in bulls.","method":"RT-PCR splice variant identification, promoter luciferase activity assay, bioinformatics domain analysis, genotype-phenotype association in Holstein bulls","journal":"Animal genetics","confidence":"Medium","confidence_rationale":"Tier 3 — promoter luciferase assay and domain analysis are functional but MIT domain essentiality is inferred bioinformatically, not tested directly","pmids":["24990491"],"is_preprint":false}],"current_model":"KATNAL1 is a microtubule-severing ATPase (katanin family) that uses its conserved AAA-ATPase domain and MIT domain to sever microtubules; it is more active and stable than its paralog KATNA1 due to its amino-terminal half, is the dominant katanin subunit in neurons and testis, co-operates with KATNA1 (scaffolded by KATNB1, with a cytoskeletal/vesicle-trafficking interactome) to regulate male meiotic spindle assembly, cytokinesis, spermatid remodelling, and Sertoli cell microtubule dynamics required for sperm retention, and also regulates neuronal process elongation and ependymal ciliary function in the CNS."},"narrative":{"teleology":[{"year":2012,"claim":"Establishing that KATNAL1 is a functional microtubule-severing enzyme required in Sertoli cells answered the question of whether this katanin paralog has non-redundant biological activity, revealing that its ATPase domain is essential and that loss of function causes male infertility through premature spermatid release.","evidence":"ENU mutagenesis in mice producing a defined ATPase-domain point mutation with Sertoli cell microtubule disruption and male-specific infertility","pmids":["22654668"],"confidence":"High","gaps":["Mechanism by which KATNAL1 regulates Sertoli cell–spermatid adhesion not defined","Relative contributions of KATNAL1 versus KATNA1 in the testis were unknown"]},{"year":2014,"claim":"Identification of a non-functional splice variant lacking the MIT domain, and a promoter SNP that increases its expression, indicated that the MIT domain is required for KATNAL1 function and that isoform ratio affects sperm morphology.","evidence":"RT-PCR splice variant cloning, promoter luciferase assays, and genotype–phenotype association in Holstein bulls","pmids":["24990491"],"confidence":"Medium","gaps":["MIT domain essentiality was inferred bioinformatically and from isoform correlation, not from direct mutagenesis","The binding partners or substrates recruited via the MIT domain are unidentified"]},{"year":2017,"claim":"Demonstrating that KATNAL1 loss disrupts ependymal motile cilia and neuronal migration expanded its role beyond the testis and established it as a regulator of CNS development.","evidence":"Loss-of-function mouse allele with ependymal cilia imaging, neuronal migration assays, and brain morphology analysis","pmids":["28373692"],"confidence":"Medium","gaps":["Molecular mechanism of KATNAL1 action in cilia biogenesis versus maintenance is unresolved","Whether CNS phenotypes are cell-autonomous has not been tested"]},{"year":2018,"claim":"Comparative biochemical analysis resolved why KATNAL1 rather than KATNA1 predominates in neurons: KATNAL1 has intrinsically higher severing activity and stability, both determined by its amino-terminal half, and its depletion specifically enhances neuronal process elongation.","evidence":"Microtubule-severing activity assays, cycloheximide chase stability measurements, chimeric domain-swap constructs, and siRNA knockdown in Neuro2a cells","pmids":["30448058"],"confidence":"High","gaps":["Structural basis for how the amino-terminal half confers higher activity and stability is unknown","Whether KATNAL1 and KATNA1 sever distinct microtubule populations in vivo has not been tested"]},{"year":2023,"claim":"Single and double knockout models together with proteomics defined the cooperative but non-redundant roles of KATNAL1 and KATNA1 throughout spermatogenesis and revealed a KATNB1-scaffolded interactome enriched in cytoskeletal and vesicle trafficking proteins.","evidence":"Single and double Katnal1/Katna1 knockout mice, mass spectrometry-based interactome analysis of KATNAL1/KATNA1/KATNB1 complexes in testis","pmids":["37882691"],"confidence":"High","gaps":["Which specific vesicle trafficking partners are direct versus indirect interactors is unresolved","How KATNB1 differentially scaffolds KATNAL1 versus KATNA1 is structurally undefined"]},{"year":2024,"claim":"Identification of miR-548az-5p as a post-transcriptional repressor of KATNAL1 in amniotic epithelial cells linked KATNAL1 suppression to microtubule disorganization, cellular senescence, and proliferation arrest, extending its functional relevance to human gestational tissues.","evidence":"miRNA microarray with target validation, KATNAL1 protein measurement after miR-548az-5p overexpression, microtubule imaging, senescence and proliferation assays in human amniotic epithelial cells","pmids":["39638877"],"confidence":"Medium","gaps":["No rescue experiment restoring KATNAL1 to confirm specificity of the miRNA-mediated phenotype","Whether miR-548az-5p–KATNAL1 axis operates in vivo during labor has not been tested"]},{"year":null,"claim":"Key unresolved questions include the structural basis for KATNAL1's enhanced activity over KATNA1, whether KATNAL1 acts on specific microtubule subtypes (e.g., acetylated, tyrosinated) in different tissues, and the direct binding partners of the MIT domain.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No crystal or cryo-EM structure of KATNAL1 exists","Microtubule post-translational modification selectivity is untested","MIT domain interactors have not been identified biochemically"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,2,4]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,3,5]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[3]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[1]}],"complexes":["Katanin complex (KATNAL1/KATNB1)"],"partners":["KATNA1","KATNB1"],"other_free_text":[]},"mechanistic_narrative":"KATNAL1 is a microtubule-severing AAA-ATPase of the katanin family that regulates microtubule dynamics in multiple cell types including Sertoli cells, neurons, ependymal cells, and spermatids. It exhibits higher severing activity and greater intracellular stability than its paralog KATNA1, properties determined by its amino-terminal half, and is the dominant katanin catalytic subunit in neurons, where its depletion enhances process elongation [PMID:30448058]. In the testis, KATNAL1 cooperates with KATNA1 (scaffolded by KATNB1) to regulate meiotic spindle assembly, cytokinesis, midbody abscission, manchette formation, sperm flagellum development, and sperm–epithelial disengagement; its loss-of-function disrupts Sertoli cell microtubule dynamics and causes male infertility [PMID:22654668, PMID:37882691]. KATNAL1 also functions in the CNS, where it is required for motile cilia assembly in ependymal cells and for normal neuronal migration [PMID:28373692]."},"prefetch_data":{"uniprot":{"accession":"Q9BW62","full_name":"Katanin p60 ATPase-containing subunit A-like 1","aliases":["p60 katanin-like 1"],"length_aa":490,"mass_kda":55.4,"function":"Regulates microtubule dynamics in Sertoli cells, a process that is essential for spermiogenesis and male fertility. Severs microtubules in an ATP-dependent manner, promoting rapid reorganization of cellular microtubule arrays (By similarity). Has microtubule-severing activity in vitro (PubMed:26929214)","subcellular_location":"Cytoplasm, cytoskeleton; Cytoplasm; Cytoplasm, cytoskeleton, spindle pole; Cytoplasm, cytoskeleton, spindle","url":"https://www.uniprot.org/uniprotkb/Q9BW62/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KATNAL1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KATNAL1","total_profiled":1310},"omim":[{"mim_id":"616235","title":"KATANIN, p80 SUBUNIT, B-LIKE 1; KATNBL1","url":"https://www.omim.org/entry/616235"},{"mim_id":"614764","title":"KATANIN, p60 SUBUNIT, A-LIKE 1; KATNAL1","url":"https://www.omim.org/entry/614764"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Centrosome","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"},{"location":"Mitotic spindle","reliability":"Additional"},{"location":"Mitochondria","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/KATNAL1"},"hgnc":{"alias_symbol":["MGC2599"],"prev_symbol":[]},"alphafold":{"accession":"Q9BW62","domains":[{"cath_id":"1.20.58.80","chopping":"2-75","consensus_level":"high","plddt":90.6591,"start":2,"end":75},{"cath_id":"3.40.50.300","chopping":"187-376","consensus_level":"high","plddt":82.4617,"start":187,"end":376},{"cath_id":"1.10.8.60","chopping":"382-471","consensus_level":"high","plddt":90.294,"start":382,"end":471}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BW62","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BW62-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BW62-F1-predicted_aligned_error_v6.png","plddt_mean":76.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KATNAL1","jax_strain_url":"https://www.jax.org/strain/search?query=KATNAL1"},"sequence":{"accession":"Q9BW62","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BW62.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BW62/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BW62"}},"corpus_meta":[{"pmid":"22654668","id":"PMC_22654668","title":"KATNAL1 regulation of sertoli cell microtubule dynamics is essential for spermiogenesis and male fertility.","date":"2012","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22654668","citation_count":65,"is_preprint":false},{"pmid":"28373692","id":"PMC_28373692","title":"A missense mutation in Katnal1 underlies behavioural, neurological and ciliary anomalies.","date":"2017","source":"Molecular psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/28373692","citation_count":34,"is_preprint":false},{"pmid":"31800303","id":"PMC_31800303","title":"Circ_KATNAL1 regulates prostate cancer cell growth and invasiveness through the miR-145-3p/WISP1 pathway.","date":"2019","source":"Biochemistry and cell biology = Biochimie et biologie cellulaire","url":"https://pubmed.ncbi.nlm.nih.gov/31800303","citation_count":31,"is_preprint":false},{"pmid":"24664804","id":"PMC_24664804","title":"A newly recognized 13q12.3 microdeletion syndrome characterized by intellectual disability, microcephaly, and eczema/atopic dermatitis encompassing the HMGB1 and KATNAL1 genes.","date":"2014","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/24664804","citation_count":27,"is_preprint":false},{"pmid":"35979014","id":"PMC_35979014","title":"circ-Katnal1 Enhances Inflammatory Pyroptosis in Sepsis-Induced Liver Injury through the miR-31-5p/GSDMD Axis.","date":"2022","source":"Mediators of inflammation","url":"https://pubmed.ncbi.nlm.nih.gov/35979014","citation_count":17,"is_preprint":false},{"pmid":"30448058","id":"PMC_30448058","title":"KATNAL1 is a more active and stable isoform of katanin, and is expressed dominantly in neurons.","date":"2018","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/30448058","citation_count":10,"is_preprint":false},{"pmid":"24990491","id":"PMC_24990491","title":"Association between an alternative promoter polymorphism and sperm deformity rate is due to modulation of the expression of KATNAL1 transcripts in Chinese Holstein bulls.","date":"2014","source":"Animal genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24990491","citation_count":9,"is_preprint":false},{"pmid":"37882691","id":"PMC_37882691","title":"The katanin A-subunits KATNA1 and KATNAL1 act co-operatively in mammalian meiosis and spermiogenesis to achieve male fertility.","date":"2023","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/37882691","citation_count":8,"is_preprint":false},{"pmid":"24913027","id":"PMC_24913027","title":"Lack of association of KATNAL1 gene sequence variants and azoospermia in humans.","date":"2014","source":"Journal of assisted reproduction and genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24913027","citation_count":6,"is_preprint":false},{"pmid":"35752927","id":"PMC_35752927","title":"Common genetic variation in KATNAL1 non-coding regions is involved in the susceptibility to severe phenotypes of male infertility.","date":"2022","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/35752927","citation_count":5,"is_preprint":false},{"pmid":"28093975","id":"PMC_28093975","title":"Molecular Modeling and Dynamics Simulation Analysis of KATNAL1 for Identification of Novel Inhibitor of Sperm Maturation.","date":"2017","source":"Combinatorial chemistry & high throughput screening","url":"https://pubmed.ncbi.nlm.nih.gov/28093975","citation_count":4,"is_preprint":false},{"pmid":"39638877","id":"PMC_39638877","title":"miR-548az-5p induces amniotic epithelial cell senescence by regulating KATNAL1 expression in labor.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39638877","citation_count":2,"is_preprint":false},{"pmid":"37715400","id":"PMC_37715400","title":"Circ_KATNAL1 promotes the inflammation and apoptosis in human middle ear epithelial cells induced by lipopolysaccharide by regulating the miR-153-3p / TLR4 axis.","date":"2023","source":"Cellular and molecular biology (Noisy-le-Grand, France)","url":"https://pubmed.ncbi.nlm.nih.gov/37715400","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8679,"output_tokens":1667,"usd":0.025521},"stage2":{"model":"claude-opus-4-6","input_tokens":4904,"output_tokens":2062,"usd":0.114105},"total_usd":0.139626,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2012,\n      \"finding\": \"KATNAL1 (Katanin p60 subunit A-like 1) functions as a microtubule-severing protein in testicular Sertoli cells; a point mutation in its conserved ATPase domain causes loss of function, disrupting Sertoli cell microtubule dynamics and leading to premature spermatid exfoliation from the seminiferous epithelium and male-specific infertility.\",\n      \"method\": \"ENU mutagenesis screen in mice, identification of ATPase domain point mutation, loss-of-function phenotypic analysis, Sertoli cell expression confirmed from 15.5 dpc\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function allele with defined molecular lesion (ATPase domain) and specific cellular phenotype, replicated with chemical disruption models\",\n      \"pmids\": [\"22654668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Loss-of-function of KATNAL1 in mice causes defects in motile cilia of ventricular ependymal cells, neuronal migration defects, and morphological brain abnormalities, establishing a role for KATNAL1 in ciliary function and CNS development.\",\n      \"method\": \"Mouse loss-of-function allele characterization, brain morphology analysis, ependymal cilia imaging, neuronal migration assays\",\n      \"journal\": \"Molecular psychiatry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO mouse with defined cellular phenotypes (cilia, neuronal migration), single lab\",\n      \"pmids\": [\"28373692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"KATNAL1 exhibits higher microtubule-severing activity and greater intracellular stability compared to its paralog KATNA1, is dominantly expressed in neurons, and its amino-terminal half region is the determinant of these functional characteristics; KATNAL1 knockdown in Neuro2a cells enhances process elongation whereas KATNA1 knockdown has no effect.\",\n      \"method\": \"Comparative expression analysis across tissues, microtubule-severing activity assays in Neuro2a cells, cycloheximide chase for stability, chimeric molecule domain-swap experiments, siRNA knockdown with process elongation readout\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro activity assay, domain-swap mutagenesis, stability assay, and KD phenotype all in one study\",\n      \"pmids\": [\"30448058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"KATNAL1 cooperates with KATNA1 to regulate the male meiotic spindle, cytokinesis, midbody abscission, and spermatid remodelling events (Golgi organisation, acrosome and manchette formation); KATNAL1 has specific roles in sperm flagellum development, manchette regulation, and sperm-epithelial disengagement. Proteomic approaches defined the KATNAL1/KATNA1/KATNB1 mammalian testis interactome, which includes cytoskeletal and vesicle trafficking proteins.\",\n      \"method\": \"Single and double gene knockout mice, proteomic interactome analysis (mass spectrometry), phenotypic characterization of meiosis and spermiogenesis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple single/double KO models plus MS-based interactome, orthogonal methods in one study\",\n      \"pmids\": [\"37882691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"miR-548az-5p targets KATNAL1 mRNA in human amniotic epithelial cells; suppression of KATNAL1 by miR-548az-5p disorganizes microtubules, increases senescence-associated secretory phenotype markers, and inhibits cell proliferation via cyclin D1 and CDK6, contributing to amniotic membrane senescence during labor.\",\n      \"method\": \"miRNA microarray, bioinformatics target prediction, miR-548az-5p overexpression with KATNAL1 measurement, microtubule imaging, senescence marker assays, proliferation assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, functional miRNA-target validation with downstream cellular readouts but no reciprocal rescue experiment for full mechanistic confirmation\",\n      \"pmids\": [\"39638877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The MIT domain of KATNAL1 is predicted to be essential for protein function; a splice variant (KATNAL1-TV2) lacking the MIT domain is non-functional, and a promoter SNP (c.163-210T>C) in the alternative promoter P2 increases expression of this non-functional isoform, correlating with higher sperm deformity rates in bulls.\",\n      \"method\": \"RT-PCR splice variant identification, promoter luciferase activity assay, bioinformatics domain analysis, genotype-phenotype association in Holstein bulls\",\n      \"journal\": \"Animal genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — promoter luciferase assay and domain analysis are functional but MIT domain essentiality is inferred bioinformatically, not tested directly\",\n      \"pmids\": [\"24990491\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KATNAL1 is a microtubule-severing ATPase (katanin family) that uses its conserved AAA-ATPase domain and MIT domain to sever microtubules; it is more active and stable than its paralog KATNA1 due to its amino-terminal half, is the dominant katanin subunit in neurons and testis, co-operates with KATNA1 (scaffolded by KATNB1, with a cytoskeletal/vesicle-trafficking interactome) to regulate male meiotic spindle assembly, cytokinesis, spermatid remodelling, and Sertoli cell microtubule dynamics required for sperm retention, and also regulates neuronal process elongation and ependymal ciliary function in the CNS.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"KATNAL1 is a microtubule-severing AAA-ATPase of the katanin family that regulates microtubule dynamics in multiple cell types including Sertoli cells, neurons, ependymal cells, and spermatids. It exhibits higher severing activity and greater intracellular stability than its paralog KATNA1, properties determined by its amino-terminal half, and is the dominant katanin catalytic subunit in neurons, where its depletion enhances process elongation [PMID:30448058]. In the testis, KATNAL1 cooperates with KATNA1 (scaffolded by KATNB1) to regulate meiotic spindle assembly, cytokinesis, midbody abscission, manchette formation, sperm flagellum development, and sperm–epithelial disengagement; its loss-of-function disrupts Sertoli cell microtubule dynamics and causes male infertility [PMID:22654668, PMID:37882691]. KATNAL1 also functions in the CNS, where it is required for motile cilia assembly in ependymal cells and for normal neuronal migration [PMID:28373692].\",\n  \"teleology\": [\n    {\n      \"year\": 2012,\n      \"claim\": \"Establishing that KATNAL1 is a functional microtubule-severing enzyme required in Sertoli cells answered the question of whether this katanin paralog has non-redundant biological activity, revealing that its ATPase domain is essential and that loss of function causes male infertility through premature spermatid release.\",\n      \"evidence\": \"ENU mutagenesis in mice producing a defined ATPase-domain point mutation with Sertoli cell microtubule disruption and male-specific infertility\",\n      \"pmids\": [\"22654668\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which KATNAL1 regulates Sertoli cell–spermatid adhesion not defined\",\n        \"Relative contributions of KATNAL1 versus KATNA1 in the testis were unknown\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identification of a non-functional splice variant lacking the MIT domain, and a promoter SNP that increases its expression, indicated that the MIT domain is required for KATNAL1 function and that isoform ratio affects sperm morphology.\",\n      \"evidence\": \"RT-PCR splice variant cloning, promoter luciferase assays, and genotype–phenotype association in Holstein bulls\",\n      \"pmids\": [\"24990491\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"MIT domain essentiality was inferred bioinformatically and from isoform correlation, not from direct mutagenesis\",\n        \"The binding partners or substrates recruited via the MIT domain are unidentified\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrating that KATNAL1 loss disrupts ependymal motile cilia and neuronal migration expanded its role beyond the testis and established it as a regulator of CNS development.\",\n      \"evidence\": \"Loss-of-function mouse allele with ependymal cilia imaging, neuronal migration assays, and brain morphology analysis\",\n      \"pmids\": [\"28373692\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular mechanism of KATNAL1 action in cilia biogenesis versus maintenance is unresolved\",\n        \"Whether CNS phenotypes are cell-autonomous has not been tested\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Comparative biochemical analysis resolved why KATNAL1 rather than KATNA1 predominates in neurons: KATNAL1 has intrinsically higher severing activity and stability, both determined by its amino-terminal half, and its depletion specifically enhances neuronal process elongation.\",\n      \"evidence\": \"Microtubule-severing activity assays, cycloheximide chase stability measurements, chimeric domain-swap constructs, and siRNA knockdown in Neuro2a cells\",\n      \"pmids\": [\"30448058\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis for how the amino-terminal half confers higher activity and stability is unknown\",\n        \"Whether KATNAL1 and KATNA1 sever distinct microtubule populations in vivo has not been tested\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Single and double knockout models together with proteomics defined the cooperative but non-redundant roles of KATNAL1 and KATNA1 throughout spermatogenesis and revealed a KATNB1-scaffolded interactome enriched in cytoskeletal and vesicle trafficking proteins.\",\n      \"evidence\": \"Single and double Katnal1/Katna1 knockout mice, mass spectrometry-based interactome analysis of KATNAL1/KATNA1/KATNB1 complexes in testis\",\n      \"pmids\": [\"37882691\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Which specific vesicle trafficking partners are direct versus indirect interactors is unresolved\",\n        \"How KATNB1 differentially scaffolds KATNAL1 versus KATNA1 is structurally undefined\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identification of miR-548az-5p as a post-transcriptional repressor of KATNAL1 in amniotic epithelial cells linked KATNAL1 suppression to microtubule disorganization, cellular senescence, and proliferation arrest, extending its functional relevance to human gestational tissues.\",\n      \"evidence\": \"miRNA microarray with target validation, KATNAL1 protein measurement after miR-548az-5p overexpression, microtubule imaging, senescence and proliferation assays in human amniotic epithelial cells\",\n      \"pmids\": [\"39638877\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No rescue experiment restoring KATNAL1 to confirm specificity of the miRNA-mediated phenotype\",\n        \"Whether miR-548az-5p–KATNAL1 axis operates in vivo during labor has not been tested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis for KATNAL1's enhanced activity over KATNA1, whether KATNAL1 acts on specific microtubule subtypes (e.g., acetylated, tyrosinated) in different tissues, and the direct binding partners of the MIT domain.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No crystal or cryo-EM structure of KATNAL1 exists\",\n        \"Microtubule post-translational modification selectivity is untested\",\n        \"MIT domain interactors have not been identified biochemically\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 2, 4]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 3, 5]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\n      \"Katanin complex (KATNAL1/KATNB1)\"\n    ],\n    \"partners\": [\n      \"KATNA1\",\n      \"KATNB1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}